Arduino + Servo

Forum 2005-2010 (read only) Software Syntax & Programs
1

Hi, my name is Guzz and i'm new on the arduino world. I'm having some trouble to write a code to control 4 servos with a arduino, and i dont know what can be wrong with my code, i'm not a programmer (yet). I wrote this code based on de sweep code from the arduino examples. ''The code compiles fine, but when i try to upload to the board it crashes. Im using the arduino duemilanove with atmega 328." - solved - The code is like this...

#include <Servo.h>

Servo myservo0;  // create servo object to control a servo
               // a maximum of eight servo objects can be created

int pos0 = 0;    // variable to store the servo position

Servo myservo1;  // create servo object to control a servo
               // a maximum of eight servo objects can be created

int pos1 = 0;    // variable to store the servo position

Servo myservo2;  // create servo object to control a servo
               // a maximum of eight servo objects can be created

int pos2 = 0;    // variable to store the servo position

Servo myservo3;  // create servo object to control a servo
               // a maximum of eight servo objects can be created

int pos3 = 0;    // variable to store the servo position

void setup()
{
 myservo0.attach(9);  // attaches the servo on pin 9 to the servo object
 myservo1.attach(8);  // attaches the servo on pin 8 to the servo object
 myservo2.attach(7);  // attaches the servo on pin 7 to the servo object
 myservo3.attach(5);  // attaches the servo on pin 5 to the servo object
}


void loop()
{
 for(pos0 = 0; pos0 < 180; pos0 += 1)  // goes from 0 degrees to 180 degrees
 {                                  // in steps of 1 degree
   myservo0.write(pos0);              // tell servo to go to position in variable 'pos'
   delay(5);                       // waits 15ms for the servo to reach the position
 }
 for(pos0 = 180; pos0>=1; pos0-=1)     // goes from 180 degrees to 0 degrees
 {                                
   myservo0.write(pos0);              // tell servo to go to position in variable 'pos'
   delay(5);                       // waits 15ms for the servo to reach the position
 }
 for(pos1 = 0; pos1 < 180; pos1 += 1)  // goes from 0 degrees to 180 degrees
 {                                  // in steps of 1 degree
   myservo1.write(pos1);              // tell servo to go to position in variable 'pos'
   delay(5);                       // waits 15ms for the servo to reach the position
 }
 for(pos1 = 180; pos1>=1; pos1-=1)     // goes from 180 degrees to 0 degrees
 {                                
   myservo1.write(pos1);              // tell servo to go to position in variable 'pos'
   delay(5);                       // waits 15ms for the servo to reach the position
 }
 for(pos2 = 0; pos2 < 180; pos2 += 1)  // goes from 0 degrees to 180 degrees
 {                                  // in steps of 1 degree
   myservo2.write(pos2);              // tell servo to go to position in variable 'pos'
   delay(5);                       // waits 15ms for the servo to reach the position
 }
 for(pos2 = 180; pos2>=1; pos2-=1)     // goes from 180 degrees to 0 degrees
 {                                
   myservo2.write(pos0);              // tell servo to go to position in variable 'pos'
   delay(5);                       // waits 15ms for the servo to reach the position
 }
 for(pos3 = 0; pos3 < 180; pos3 += 1)  // goes from 0 degrees to 180 degrees
 {                                  // in steps of 1 degree
   myservo3.write(pos3);              // tell servo to go to position in variable 'pos'
   delay(5);                       // waits 15ms for the servo to reach the position
 }
 for(pos3 = 180; pos3>=1; pos3-=1)     // goes from 180 degrees to 0 degrees
 {                                
   myservo3.write(pos3);              // tell servo to go to position in variable 'pos'
   delay(5);                       // waits 15ms for the servo to reach the position
 }
}

This code is working fine, but is not doing what i wanted. Each one of the servos moves one at a time, how could i make them move at the same time?

AWOL gave me some help and rewrote this sketch for me to simplify it,

#include <Servo.h>

Servo myservo [4];  // create servo object to control four servos

int pos [4] = 0;    // variable to store the servo position

void setup()
{
  myservo[0].attach(9);  // attaches the servo on pin 9 to a servo object
  myservo[1].attach(8);  // attaches the servo on pin 8 to a servo object
  myservo[2].attach(7);  // attaches the servo on pin 7 to a servo object
  myservo[3].attach(5);  // attaches the servo on pin 5 to a servo object
}

void loop()
{
  for (int i = 0; i < 4; ++i) {
      for(pos[i] = 0; pos[i] < 180; pos[i] += 1)
    {
       myservo[i].write(pos[i]);
       delay(5);                       // waits 5ms for the servo to reach the position
    }
    for(pos[i] = 180; pos[i]>=1; pos[i]-=1)     // goes from 180 degrees to 0 degrees
    {
       myservo[i].write(pos[i]);              // tell servo to go to position in variable 'pos'
       delay(5);                       // waits 5ms for the servo to reach the position
    }
  }
}

but when i try to compile it i get the message

error: array must be initialized with a brace-enclosed initializer

in the int pos [4] = 0; line

Can someone tell me how can i fix this?

Thanks AWOL for all your help :slight_smile:
and thanks everybody

2

Hi,

try this

#include <Servo.h>

Servo myservo [4];  // create servo object to control four servos

int pos [4] = {0};    // variable to store the servo position
int maxpos[4] = {180,120,220,180}; // max. position for each servo
int dir[4] = {1}; // count direction for each servo


void setup()
{
  myservo[0].attach(9);  // attaches the servo on pin 9 to a servo object
  myservo[1].attach(8);  // attaches the servo on pin 8 to a servo object
  myservo[2].attach(7);  // attaches the servo on pin 7 to a servo object
  myservo[3].attach(5);  // attaches the servo on pin 5 to a servo object
}

void loop()
{
  // process all 4 servos
  for (int i = 0; i < 4; i++) {
    // increment or decrement pos value
    pos[i] += dir[i];
    // if the pos reaches the upper limit, change the direction to -
    if (pos[i] >= maxpos[i]) dir[i] = -1;
    // if pos reaches the lower end, change direction to +
    if (pos[i] <= 0) dir[i] = 1;
    // set the value for the servo  
    myservo[i].write(pos[i]);
  }
  // now all servos have a new value, delay for 5ms
  delay(5);
}

You can set a different max value for each of the servos.

Mike

3

Guzz, can you please delete your duplicate posts - it wastes people's time to respond to questions that have already been answered.